SAN DIEGO (AP) — A man arrested after a homemade cannon blasted through his mobile home, killing his girlfriend, “liked to live life on the edge,” his brother told a San Diego newspaper.

Richard Fox, 39, was arrested for investigation of exploding a device resulting in death after the Tuesday blast in a mountain community near San Diego, sheriff ’s Sgt. David Martinez said.

Fox’s 38-year-old girlfriend was found dead from shrapnel wounds when authorities arrived at the home.

Richard Fox’s brother, Jerry Fox, told U-T San Diego he spoke with his anguished brother by phone moments after the blast.

“ I’m sorry. I’m sorry. It should have been me,” Jerry Fox said, recounting his brother’s words.

Richard Fox shot the cannon after loading it with fireworks powder, Martinez said. He was treated at a hospital for shrapnel wounds to his right leg. Three other adults and a 4- year-old girl who were inside the home escaped injury.

Preliminary evidence suggested Richard Fox was under the influence of alcohol, Martinez said. Investigators had not established a motive or determined if the blast was accidental.

“He gave us his version of the story. We want to corroborate that based on the evidence we find at the scene,” Martinez said.

It was unclear if Richard Fox had an attorney.

Richard Fox lived at the home with his girlfriend, whose name was not released, and the 4-year-old girl, who was to be placed with a relative. Martinez declined to identify the three other adults who were inside the home.

The blast occurred in Potrero, a community of about 700 people on the Mexican border, about 40 miles east of San Diego. In 2008, military contractor Blackwater Worldwide pulled plans for a training facility there after voters recalled five members of a planning board who supported the project.

John Arnold, a neighbor, told U- T San Diego that Richard Fox worked as a handyman and lived in the home for about six years.

“ He liked experimenting with guns, and it looks like this experiment went bad,” he told the newspaper.

Sandra Barranon, who lives at the mobile home park, told U-T San Diego she knew the couple for about 10 years. They were not married, she said.

The woman who died was unemployed, enjoyed doing The New York Times crossword puzzle, and kept the trailer neat and clean, Barranon said.